After Duffus McClutski's wife made him give up his used tea bag collection, Duffus decided to start collecting fridge magnets. Eventually, he had enough to cover the entire fridge, much to his wife's dismay. After several failed attempts to get rid of them, she finally gave up until one day, their fridge broke down. They looked at dozens of fridges, but finally settled on a top-of-the-line stainless steel model with two doors, icemaker and the works. Duffus was reluctant to spend so much on a fridge till his wife told him to imagine how great his fridge magnets would look on it. That was all the motivation he needed, but once the fridge was in, he soon realized his wife had put one over on him, and he would only be able to imagine his collection on the fridge from now on.
But why, what had she done?

Hint

Answer

She knew that high quality stainless steel like that used in making expensive pots, cooking utensils, and fridges is non-magnetic. Thus the fridge magnets wouldn't stick and Duffus would have to take up a new hobby. But that's another teaser.Hide

We do have a stainless fridge, and magnets do stick on them. My guess is high quality stainless for other applications is not magnetic, but the quality of stainless on some (most?) fridges do contain iron.